Johannes Kepler was easily one of the most influential scientists of the 17th century scientific revolution. His studies combined astronomy, physics, and religion together during a time where all three subjects were considered separate. One of his biggest contributions to physics were his three laws of planetary motion. Initially Kepler's studies were given little thought, at least until the respected astronomer Tycho Brahe invited Kepler to work with him in Prague. This allowed for him to meet with other well-known scholars, and eventually led to his discovery that the planets followed an elliptical path as opposed to a circular path that Nicolaus Copernicus had originally established. He established these discoveries in a number of books, such as Mysterium Cosmographicum, Astronomiae Pars Optica, and Astronomia nova.
Insight and Influences
Image courtesy of BCSEngage
Johannes Kepler was born in Weil der Stadt near Stuttgart, Germany on December 27, 1571. His father, Heinrich Kepler, lived a dangerous life as a mercenary and left when Johannes was only 5 years old. It's likely that Heinrich died in the Netherlands during the Eighty Years' War. His mother, Katharina Kepler, was a healer and an herbalist, who was later put on trial under the accusation that she was a witch.[¹] When talking about his parents, Kepler stated that he wasn't too fond of his father for leaving his family so early in his life, with similarly negative remarks about his mother. Being born prematurely, Kepler stated that he grew up weak and sickly. However, he was said to have been quite brilliant for such a young age. He demonstrated this intelligence to various travelers at his grandfather's inn, who were often shocked by his impressive mathematical ability. [¹]
Kepler developed a love for astronomy at a very young age, beginning when he viewed the Great Comet of 1577 when he was six years old. Recalling this, Kepler remembers being taken to a high place by his mother to see it. Three years later, he witnessed a lunar eclipse, which he later would say that the moon "appeared quite red". However, Kepler would have difficulty actually observing events in astronomy, caused by his childhood smallpox that left his eyes weak and his hands crippled. [³] Fortunately, this didn't deter him from continuing his studies later on in his life.
After Kepler completed grammar school, Latin school, as well as lower and higher seminary in the Württemberg state-run Protestant education system, he began to attend the University of Tübingen in 1589 as a theology student under the instruction of Vitus Müller. [¹] He quickly established himself as a skillful mathematician and astronomer among his fellow peers. During this time, Kepler was also instructed by Michael Maestlin, who taught the Ptolemaic system and the Copernican system of planetary motion to him. Kepler was inspired by the Copernican system, which became a major influence in his life and work. The works of Nicolaus Copernicus would continue to inspire Kepler even as he continued his studies throughout the rest of his life. [²] At another point while at the university, he defended heliocentrism in a student disputation from both a theoretical and a theological standpoint. [⁶] This would also become a familiar trait of Kepler's ideals; to combine astronomy with religion in such an intriguing manner. After graduating in 1591, Kepler was offered a position as a teacher of mathematics and astronomy at the Protestant school in Graz, Austria. He finally accepted this position in 1594, at the age of 23, and moved to Graz, Austria. [³]
While teaching in Graz, Kepler claimed to have an epiphany related to the distances between the planets. In 1596, Kepler publishedMysterium Cosmographicum(literally meaning,The Cosmographic Mystery), which is considered to be his first major work in astrology. Interestingly, it was also the first published work defending the Copernican idea of heliocentrism. With this, Kepler described how the five Platonic solids could be arranged in a way to determine the orbits and distances of the six known planets in the solar system. This piece of work likely caught the attention of astronomers, with Tycho Brahe being an important figure in particular.
Major Contributions
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Shortly after publishing the Mysterium Cosmographicum, Tycho Brahe invited Johannes Kepler to work with him in Prague in December of 1599. However, Kepler left for Prague on January 1, 1600 before he even recieved the invitation. [³] He arrived on February 4 of that same year, and the two astronomers became fast friends. Tycho Brahe originally kept most of his research hidden from Kepler, but was soon impressed with his theoretical ideals, and soon let him have more access. The two had an argument regarding Kepler's employment and living conditions to Tycho, but they soon came to an agreement and Kepler returned to Graz to bring the rest of his family to Prague. However, political and religious issues within Graz would delay Kepler's return to Prague by a few months. During this time, he composed an idea that basically stated, "There is a force in the earth which causes the moon to move." [³] This would later become a major factor in Kepler's later work Astronomiae Pars Optica. He finally returned to Prague and was directly supported by Tycho throughout most of 1601. Tycho would assign planetary observations for Kepler to analyze, and even acquired Kepler a spot on the collaboration Rudolphine Tables. Tycho unexpectedly died on October 24, 1601, and Kepler was quickly named his successor. He was also appointed as an imperial mathematician and advisor to Emperor Rudolph II. [³] He was to give astronomical advice to the emperor, but he usually just advised common sense in most situations.
During his time as the emperor's advisor, Kepler was able to further analyze the research that Tycho Brahe had worked on. He also got the chance to meet other important scholars, including Johannes Matthäus Wackher von Wackhenfels, Jost Bürgi, David Fabricius, Martin Bachazek, and Johannes Brengger. This period of time was where Kepler made the most progress in his studies. [³] On January 1, 1604, he presented a manuscript to the emperor, which would later be published as Astronomiae Pars Optica (literally meaning, The Optical Part of Astronomy). In this, Kepler described the laws of governing light, and the effect on differently positioned mirrors. He also went into detail on human optics, and how the eyes absorb and interpret light. Even today, many consider Kepler's Astronomiae Pars Optica to be the foundation of modern optics. [³]
Kepler's continued analysis of Tycho Brahe's research of Mars's orbit eventually led to an amazing discovery. While trying to determine the orbit of Mars, Kepler decided to act on a hunch. He used the Tycho's data on Mars, and tried using an elliptical orbit to see if the data matched up. He was successful, and Kepler used this for his first law of planetary motion, that all planets followed elliptical orbits. Around this same time, he also created the second law of planetary motion, which states that the planets sweep out in equal areas in equal times. He established both of these laws in what many consider to be his greatest work, Astronomia nova (literally meaning, A New Astronomy), which actually wouldn't be published until 1609.
Affect and Effect
Possibly due to his separated parents in his childhood, Kepler's marriage with Barbara Müller was somewhat strained. Their relationship continued in this manner until Barbara's death by Hungarian spotted fever in 1611. In October of 1613, Kepler married Susanna Reuttinger after much consideration of 11 possible matches. Kepler said that he chose Susana because she "won me over with love, humble loyalty, economy of household, diligence, and the love she gave the stepchildren." [⁴] This marriage was said by several biographers to be more pleasant than the first. [³] Kepler didn't say much about his children, sadly, as a large number of them died at young ages from diseases such as smallpox. Among other astronomers that he worked with, Johannes Kepler and Tycho Brahe had a relationship of respect for each other during the years that they worked together. They had the occasional argument regarding salary and living conditions, and Tycho was initially hesitant to let Kepler look at his research, but Tycho came to have a greater respect for Kepler's intelligence and soon allowed for him to look over more of his notes. Tycho's notes on Mars in particular were a very important factor in Kepler's later studies and discoveries regarding his laws of planetary motion. Then there were the large number of people who Kepler met during his time at the University of Tübingen and during his time as the imperial mathematician to Emperor Rudolph II and later, the Holy Roman Emperor Matthias. These people were often impressed by Kepler's knowledge of astronomy, as he often created horoscopes for his friends, classmates, and other imperial members of the emperor's court. The emperors themselves had a high amount of respect for Kepler, allowing for him to keep his religious beliefs and practices of Lutheranism.
Kepler's laws of planetary motion were influential to many other astronomers throughout most of the 17th century. Two well-known astronomers, Pierre Gassendi and Jeremiah Horrocks, observed the transits of Mercury in 1631 and Venus in 1639, respectively, both of which confirmed the predictions that Kepler had made many years earlier. [⁷] Jeremiah Horrocks was deeply influenced by Kepler's works and was a strict advocate of the Keplerian model. [⁸] In some cases, Kepler's studies and works affected other physicists without their even knowing. Galileo Galilei essentially ignored Kepler's works entirely, yet was completely unaware that Kepler's studies in the areas of optics in fact legitimized his own discoveries with telescopes. A large number of Kepler's studies and discoveries, especially his works on the elliptical orbits of planets were documented in the textbook Epitome of Copernican Astronomy, which was widely spread across Europe throughout the 17th century, and became the most used textbook between 1630 and 1650. Giovanni Alfonso Borelli and Robert Hooke both built up their astronomical ideas from the foundations of Kepler's works as well. What is perhaps one of the biggest effects of Kepler's studies were their inclusion in Sir Isaac Newton'sPrincipia Mathematica, in which Newton described that Kepler's laws of planetary motion were part of the basis for the much larger theory of universal gravitation. [⁹]
The Things He Left Behind
Image courtesy of The Alchemy Web Site
Johannes Kepler died on November 15, 1630, and left behind an impressive legacy that continues to impact us even today. The most important contributions that Kepler made to the scientific world were his three laws of planetary motion. The first law, that the planets follow an elliptical orbit is perhaps the most important and well-known of the three laws. [⁵] This discovery of elliptical orbits was considered to be a major change within the scientific community, as it was the first legitimate opposition to Nicholas Copernicus's circular orbits that he established many years ago in the 16th century. Kepler's second law, which states a planet's orbit moves around the sun at equal time intervals, is lesser known, but still incredibly important. [⁵] This law explains the process that takes place when a planet moves slower when it's closer to the sun and faster when it's farther away. Finally, Kepler's third law explains the relationship between the distances between the planets and the sun, and how this relates to their orbits. Or, to be more specific, it states that "the square of the orbital period T is proportional to the cube of the mean distance a from the Sun (half the sum of greatest and smallest distances)", as explained by the Polar Wind Geotail. [⁵] This relation between the distances and orbits of the planets and the sun were a major factor in explaining and understanding Kepler's studies of elliptical orbits. Each of Kepler's three laws was incredibly important within his research and other astronomical discoveries, as well as becoming the general knowledge of planetary orbits even after his death. What's even more impressive is that Kepler figured out each of his three laws without the use of a telescope, simply by using logic, educated guess, and advanced mathematical equations. And so, once telescopes became widely used, all three of Kepler's laws were confirmed to be legitimate. Even to this day, there haven't been any major flaws or facts of Kepler's laws that have been proven to be false. In consideration of what Kepler's second biggest contribution to science would be, it would easily be the work he did in regards to the human eye. Kepler's Astronomiae Pars Optica explained his studies of the eye in comparison with how light is seen throughout space, and yet is still considered today to be the foundation of modern optics. The author Max Casper studied articles of Kepler's life and published a biography of his life in 1948, which is highly considered to be the important book in regards to the sheer amount of information provided about Kepler's life, studies, and discoveries. [³] By way of his incredible studies and discoveries, as well as the legacy that people continue to speak of today, Johannes Kepler's place among great astronomers, physicists, and scientists is well assured.
Table of Contents
Johannes Kepler
Johannes Kepler was easily one of the most influential scientists of the 17th century scientific revolution. His studies combined astronomy, physics, and religion together during a time where all three subjects were considered separate. One of his biggest contributions to physics were his three laws of planetary motion. Initially Kepler's studies were given little thought, at least until the respected astronomer Tycho Brahe invited Kepler to work with him in Prague. This allowed for him to meet with other well-known scholars, and eventually led to his discovery that the planets followed an elliptical path as opposed to a circular path that Nicolaus Copernicus had originally established. He established these discoveries in a number of books, such as Mysterium Cosmographicum, Astronomiae Pars Optica, and Astronomia nova.
Insight and Influences
Kepler developed a love for astronomy at a very young age, beginning when he viewed the Great Comet of 1577 when he was six years old. Recalling this, Kepler remembers being taken to a high place by his mother to see it. Three years later, he witnessed a lunar eclipse, which he later would say that the moon "appeared quite red". However, Kepler would have difficulty actually observing events in astronomy, caused by his childhood smallpox that left his eyes weak and his hands crippled. [³] Fortunately, this didn't deter him from continuing his studies later on in his life.
After Kepler completed grammar school, Latin school, as well as lower and higher seminary in the Württemberg state-run Protestant education system, he began to attend the University of Tübingen in 1589 as a theology student under the instruction of Vitus Müller. [¹] He quickly established himself as a skillful mathematician and astronomer among his fellow peers. During this time, Kepler was also instructed by Michael Maestlin, who taught the Ptolemaic system and the Copernican system of planetary motion to him. Kepler was inspired by the Copernican system, which became a major influence in his life and work. The works of Nicolaus Copernicus would continue to inspire Kepler even as he continued his studies throughout the rest of his life. [²] At another point while at the university, he defended heliocentrism in a student disputation from both a theoretical and a theological standpoint. [⁶] This would also become a familiar trait of Kepler's ideals; to combine astronomy with religion in such an intriguing manner. After graduating in 1591, Kepler was offered a position as a teacher of mathematics and astronomy at the Protestant school in Graz, Austria. He finally accepted this position in 1594, at the age of 23, and moved to Graz, Austria. [³]
While teaching in Graz, Kepler claimed to have an epiphany related to the distances between the planets. In 1596, Kepler published Mysterium Cosmographicum (literally meaning, The Cosmographic Mystery), which is considered to be his first major work in astrology. Interestingly, it was also the first published work defending the Copernican idea of heliocentrism. With this, Kepler described how the five Platonic solids could be arranged in a way to determine the orbits and distances of the six known planets in the solar system. This piece of work likely caught the attention of astronomers, with Tycho Brahe being an important figure in particular.
Major Contributions
During his time as the emperor's advisor, Kepler was able to further analyze the research that Tycho Brahe had worked on. He also got the chance to meet other important scholars, including Johannes Matthäus Wackher von Wackhenfels, Jost Bürgi, David Fabricius, Martin Bachazek, and Johannes Brengger. This period of time was where Kepler made the most progress in his studies. [³] On January 1, 1604, he presented a manuscript to the emperor, which would later be published as Astronomiae Pars Optica (literally meaning, The Optical Part of Astronomy). In this, Kepler described the laws of governing light, and the effect on differently positioned mirrors. He also went into detail on human optics, and how the eyes absorb and interpret light. Even today, many consider Kepler's Astronomiae Pars Optica to be the foundation of modern optics. [³]
Kepler's continued analysis of Tycho Brahe's research of Mars's orbit eventually led to an amazing discovery. While trying to determine the orbit of Mars, Kepler decided to act on a hunch. He used the Tycho's data on Mars, and tried using an elliptical orbit to see if the data matched up. He was successful, and Kepler used this for his first law of planetary motion, that all planets followed elliptical orbits. Around this same time, he also created the second law of planetary motion, which states that the planets sweep out in equal areas in equal times. He established both of these laws in what many consider to be his greatest work, Astronomia nova (literally meaning, A New Astronomy), which actually wouldn't be published until 1609.
Affect and Effect
Possibly due to his separated parents in his childhood, Kepler's marriage with Barbara Müller was somewhat strained. Their relationship continued in this manner until Barbara's death by Hungarian spotted fever in 1611. In October of 1613, Kepler married Susanna Reuttinger after much consideration of 11 possible matches. Kepler said that he chose Susana because she "won me over with love, humble loyalty, economy of household, diligence, and the love she gave the stepchildren." [⁴] This marriage was said by several biographers to be more pleasant than the first. [³] Kepler didn't say much about his children, sadly, as a large number of them died at young ages from diseases such as smallpox. Among other astronomers that he worked with, Johannes Kepler and Tycho Brahe had a relationship of respect for each other during the years that they worked together. They had the occasional argument regarding salary and living conditions, and Tycho was initially hesitant to let Kepler look at his research, but Tycho came to have a greater respect for Kepler's intelligence and soon allowed for him to look over more of his notes. Tycho's notes on Mars in particular were a very important factor in Kepler's later studies and discoveries regarding his laws of planetary motion. Then there were the large number of people who Kepler met during his time at the University of Tübingen and during his time as the imperial mathematician to Emperor Rudolph II and later, the Holy Roman Emperor Matthias. These people were often impressed by Kepler's knowledge of astronomy, as he often created horoscopes for his friends, classmates, and other imperial members of the emperor's court. The emperors themselves had a high amount of respect for Kepler, allowing for him to keep his religious beliefs and practices of Lutheranism.
Kepler's laws of planetary motion were influential to many other astronomers throughout most of the 17th century. Two well-known astronomers, Pierre Gassendi and Jeremiah Horrocks, observed the transits of Mercury in 1631 and Venus in 1639, respectively, both of which confirmed the predictions that Kepler had made many years earlier. [⁷] Jeremiah Horrocks was deeply influenced by Kepler's works and was a strict advocate of the Keplerian model. [⁸] In some cases, Kepler's studies and works affected other physicists without their even knowing. Galileo Galilei essentially ignored Kepler's works entirely, yet was completely unaware that Kepler's studies in the areas of optics in fact legitimized his own discoveries with telescopes. A large number of Kepler's studies and discoveries, especially his works on the elliptical orbits of planets were documented in the textbook Epitome of Copernican Astronomy, which was widely spread across Europe throughout the 17th century, and became the most used textbook between 1630 and 1650. Giovanni Alfonso Borelli and Robert Hooke both built up their astronomical ideas from the foundations of Kepler's works as well. What is perhaps one of the biggest effects of Kepler's studies were their inclusion in Sir Isaac Newton's Principia Mathematica, in which Newton described that Kepler's laws of planetary motion were part of the basis for the much larger theory of universal gravitation. [⁹]
The Things He Left Behind
References
1. http://www.gap-system.org/~history/Biographies/Kepler.html
2. http://www.notablebiographies.com/Jo-Ki/Kepler-Johannes.html
3. Kepler, by Max Casper
4. Kepler's Witch, by James A. Connor
5. http://www-istp.gsfc.nasa.gov/stargaze/Skeplaws.htm
6. "Kepler's Early Physico-Astrological Problematic" by Robert S. Westman
7. "The Importance of the Transit of Mercury of 1631" by Albert van Helden
8. "Jeremiah Horrocks, the transit of Venus, and the 'New Astronomy' in early 17th-century England" by Allan Chapman
9. The Copernican Revolution by Thomas S. Kuhn